JPS6280572A - Magnetic detector - Google Patents

Abstract

PURPOSE:To detect a weak magnetic field and its direction by arranging a soft magnetic body which is split by >=1 slit on both or one sides of a magneto- resistance element so that the long axes of the element and soft magnetic body cross each other at right angles. CONSTITUTION:A magnetic detector is so formed that a barber pole type magneto-resistance element 11 is formed on a substrate and the soft magnetic body 13 which is split by >=1 slit 12 is formed on both or one side of the element while having its long axis perpendicularly to that of the element 11. When an external magnetic field is applied, the soft magnetic body 13 is magnetized and magnetic flux is produced at its end part and crosses the element 11, so a large output is obtained from the element 1 with the small magnetic field. The magnetism is held as it is, so the direction of the magnetic field is also detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [4] A magnetic detector that can be operated by a minute magnetic field by arranging a soft magnetic material having one or more slits near a magnetic resistance element.

[Industrial application field]

The present invention relates to a magnetic detector using a ferromagnetic magnetoresistive element, and more specifically, to a magnetic detector that can operate with a minute magnetic field.

[Conventional technology]

Ferromagnetic magnetoresistive elements are widely used as magnetic detectors together with Hall elements using semiconductor materials.

The following two methods have been used to detect magnetic fields using conventional magnetoresistive elements:
There are two ways. The first method is to detect the magnetic field by reversing the magnetization direction M of the meander-shaped magnetic ribbon l, as shown in Figure 3.The second method is to detect the magnetic field by reversing the magnetization direction M of the meander-shaped magnetic ribbon l. This method uses a magnetoresistive element having an angle of 30 to 60 degrees, for example, a barber pole type magnetoresistive element. As shown in Fig. 4, the barber pole type magnetoresistive element is made by attaching conductive thin strips 3 diagonally at regular intervals on a soft magnetic thin strip 2 which is folded in a zigzag manner and has been given uniaxial magnetic anisotropy. Since it is shaped like a barber pole, the direction of magnetization is parallel to the zigzag pattern as shown by M. When an external magnetic field Hex is applied in a direction perpendicular to this, the magnetization M, which was initially parallel to the pattern, gradually tilts as the external magnetic field Hex increases, and when a strong magnetic field is applied, the magnetization Hs is finally the same as the external magnetic field Hex. becomes. Figure 5 is a diagram showing the relationship between the magnetization direction M and the magnetoresistive effect at this time (the angle θ formed by the magnetization direction M due to the external magnetic field Hex with respect to the current i flowing in a zigzag pattern as shown in al). , π/4 → π from 0 degree as shown in (b)
/2→π3/4−π..., the direction of magnetization M
The magnetoresistive effect is maximum when the angle θ between current i and current i is 0 degrees and 180 degrees, that is, they are parallel, and the magnetoresistive effect is minimum at 90 degrees, that is, when they are perpendicular to each other. By measuring the potential difference between the re-output terminals of such a zigzag pattern, the magnitude and polarity of the magnetic field can be detected.

[Problems to be Solved by the Invention] In the conventional magnetic detection method described above, in the method using the first magnetoresistive element, when the reversal of magnetization occurs, the output is obtained and the state is maintained or determined. In addition, the second barber pole type magnetoresistive element has a problem in that the output is small in a weak magnetic field.

The present invention was created in view of these points, and an object of the present invention is to provide a magnetic detector that operates in a minute magnetic field and can also detect the history and direction of the magnetic field.

[Means for solving problems]

Therefore, the present invention provides a magnetic detector using a magnetoresistive element in which magnetization and current form an angle of about 30 to 60 degrees when no measurement magnetic field is applied, and one or more magnetoresistive elements are provided on both sides or one side of the magnetoresistive element 11. The soft magnetic material 13 divided by the slits 12 is arranged so that the long axes of the element and the soft magnetic material are perpendicular to each other.

[For production]

When an external magnetic field is applied to a soft magnetic material arranged perpendicularly to both sides or one side of an element such as a barber-pole magnetoresistive element in which the magnetization and current form an approximately 45 degree angle when no measurement magnetic field is applied, the soft magnetic material becomes magnetized and magnetic flux is generated from its end,
Because the magnetic flux crosses the element, greater detection power can be obtained than in the past.

Furthermore, since the magnetization state is maintained as it is, it becomes possible to detect the direction of the external magnetic field.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, in which a is a plan view;
b is a front view. In the figure, 10 is a substrate, 11 is a barber pole magnetoresistive element, 12 is a slit, and 13 is a soft magnetic material.

In this embodiment, as shown in FIG. 1, a barber-pole type magnetoresistive element 11 (similar to that explained in the conventional example in FIG. 4) is formed on a substrate 10, and on both sides or one side thereof (
A rectangular soft magnetic body 13 divided by slits 12 is arranged on both sides (in the figure). However, slit 1
The direction 2 is perpendicular to the longitudinal direction of the pattern of the magnetoresistive element 11.

Note that this example can be manufactured as follows.

First, a zigzag thin strip made of permalloy with a thickness of about 500 layers is formed on a silicon substrate 10 whose surface has been oxidized, using lithography technology, and an adhesive layer T is formed on this thin strip.
Au tilted by 30 to 60 degrees (mainly 45 degrees) through i and Cr
Form a pattern at equal intervals, and then add Sing, 5
A protective film of i3Nn or the like is deposited to fabricate a barber pole type magnetoresistive element 11. Next, a soft magnetic material 13 such as permalloy or Co--Zr is formed on both sides or one side of this element 11 by vapor deposition or sputtering to a thickness of several micrometers. Note that the soft magnetic material 13 is not limited to a thin film;
- A block of Zn ferrite material or the like may be used.

In this embodiment configured in this way, when an external magnetic field is applied, the soft magnetic body 13 is magnetized, and a magnetic flux is generated from its end.
Since this magnetic flux crosses the barber-pole magnetoresistive element 11, a large output can be obtained from the barber-pole magnetoresistive element 11 with a small operating magnetic field.

FIG. 2 is a diagram showing its output characteristics. In the same figure,
The horizontal axis represents the external magnetic field, and the vertical axis represents the output. The solid line A represents the characteristics of this example, and the dotted line B represents the characteristics when there is no soft magnetic material. As shown in the figure, when the external magnetic field is H, the output without the soft magnetic material is a', but in the case of this embodiment, a larger than a' is obtained. Further, in this embodiment, since the magnetization state is maintained as it is, it becomes possible to detect the direction of the external magnetic field as well. If a magnetic field -H in the opposite direction is applied, an output at point b in FIG. 2 is obtained.

At this time, the sulin l-12 provided in the soft magnetic body 13 reduces the demagnetizing field of the soft magnetic body 13, so that it is magnetized with a weaker magnetic field and a large output can be obtained. (The demagnetizing field decreases in almost inverse proportion to its width.) At the same time, the length of the soft magnetic material can be shortened, allowing for miniaturization.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to detect a minute magnetic field and its direction with a very simple configuration, and it is extremely useful in practice.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing output characteristics of an embodiment of the present invention, Fig. 3 is a diagram showing a conventional magnetoresistive element, and Fig. 4 is a diagram showing a conventional barber pole. Fig. 5 is a diagram showing the magnetic detection action of the barber pole type magnetoresistive element. In FIG. 1, 10 is a substrate, 11 is a barber pole magnetoresistive element, 12 is a slit, and 13 is a soft magnetic material. → External magnetic field Diagram showing an embodiment of the present invention First country Diagram showing the output characteristics of an embodiment of the present invention FIG. 2 Diagram showing a conventional magnetoresistive element

Claims (1)

[Claims] 1. When no measurement magnetic field is applied, the magnetization and current are approximately 3
A magnetic detector using a magnetoresistive element forming an angle of 0 to 60 degrees, the soft magnetic body (13) being divided by one or more slits (12) on both sides or one side of the magnetoresistive element (11). A magnetic detector characterized in that the elements are arranged so that the long axes of the element and the soft magnetic material are perpendicular to each other. 2. The magnetic detector according to claim 1, characterized in that a barber pole type element is used as the magnetoresistive element.